1. Field of the invention
The present invention relates to a combustor for use in an external combustion engine having a rotary-type regenerator heat exchanger.
2. Description of the Prior Art
Conventional combustors for use in external combustion engines having rotary-type regenerator heat exchangers comprise a combustion chamber defined in a housing and having heater pipes disposed on an inner circumference thereof over an angle of 360.degree., a ring-shaped regenerator rotatably supported in front of the combustion chamber and having a number of axial through holes, and air and exhaust chambers connected through the regenerator to the combustion chamber and defined in semicircular shapes. The regenerator serves to absorb the heat of a high-temperature exhaust gas discharged from the combustion chamber and to heat air introduced from the air chamber into the combustion chamber.
The regenerator includes a semicircular half portion normally positioned on the side of the exhaust chamber, with the other semicircular half portion normally positioned on the side of the air chamber. When the regenerator is rotated by a motor, it temporarily absorbs the heat of the exhaust gas from the exhaust chamber. Upon rotation of he regenerator to a 180.degree.-position, the absorbed heat is radiated into an air flow utilized for combustion. Since the combustion air flow to be supplied into the combustion chamber is heated before it is actually delivered to the combustion chamber, the combustion efficiency in the combustion chamber is increased. However, inasmuch as one of the semicircular halves of the regenerator is positioned on the exhaust chamber side while the other semicircular half is on the air chamber side, the combustion gas in the combustion chamber that is of a transversely circular cross-sectional shape tends to flow out closer to the exhaust chamber side than its central area, and the flame within the combustion chamber fails to be uniformly spread from its center radially outwardly toward the circumference thereof through 360.degree.. The heater pipes in the combustion chamber are subject to localized heating at portions thereof that are located in the direction in which the flame flows.
Seals are disposed between the housing and the opposite end surfaces of the heat regenerator body to provide hermetic sealing between these components. These seals are biased by springs in order to maintain the desired sealing capability even when the seals are worn. One problem with these seal springs is that they undergo thermally induced fatigue arising from exposure to the high-temperature exhaust gas, resulting in reduced resiliency and, hence, a reduction in the biasing force applied to bias the seals. This means that the desired excellent sealing ability cannot be maintained for a long period of time.